Final answer:
Margins of safety refer to the necessary safety precautions for pedestrians when crossing the road, factoring in vehicle speed and distance. A car traveling at 60 km/hr and 28 m away is about 8 car lengths, which could be considered a safe distance for crossing if the pedestrian can complete the crossing in time. Stopping distances for vehicles vary and are affected by road conditions and driver reaction time.
Step-by-step explanation:
Margins of safety are important considerations in various aspects of daily life, including when crossing the road in towns and cities where the speed limit is typically 60 km/hr. The concept of a margin of safety in this context refers to the necessary precautions one should take into account to maintain safety while crossing a road, especially when considering factors such as visibility, time, and space to maneuver safely.
To ensure it is safe to cross a road, one needs to consider the speed at which vehicles are traveling and their distance from the pedestrian. If a car is traveling at 60 km/hr and you need to be able to walk at least 4 m to cross safely before the car reaches you, this requires calculating the time it would take for the car to cover the distance at which a pedestrian can safely cross.
For example, if a car is 28 m away (equivalent to the length of about 8 average-sized cars), and you can cross the road in the time it would take the car to travel this distance, then it may be considered safe to cross.
Driver reaction time and road conditions significantly affect the stopping distance of a vehicle. It is registered that the stopping distance varies on dry and wet pavement, and this data is crucial for determining safety margins when considering crossing in front of an oncoming vehicle.
Generally, traffic laws and signals, such as speed limits and pedestrian crossings, are designed to create safe margins, but it is still essential for pedestrians to make careful judgments based on observed conditions.